Overview

Interface parameters

Interface parameters are configuration settings that

  • define the operational characteristics of network interfaces,

  • enable administrators to tailor interface behavior for specific roles, and

  • support enhancements to performance, security, and connectivity.

Cisco NX-OS supports multiple configuration parameters for each supported interface type. Most of these parameters are described in this guide. Some parameters are described in other documents

The table provides sources for more information about configurable interface parameters.

Table 1. Interface Parameters

Feature

Parameters

Further Information

Basic parameters

Description, duplex, error disable, flow control, MTU, beacon

“Configuring Basic Interface Parameters”

Layer 3

Medium, IPv4 and IPv6 addresses

“Configuring Layer 3 Interfaces”

Layer 3

Bandwidth, delay, IP routing, Virtual Routing and Forwarding (VRFs)

Cisco Nexus 9000 Series NX-OS Unicast Routing Configuration Guide

Cisco Nexus 9000 Series NX-OS Multicast Routing Configuration Guide

Port channels

Channel group, Link Aggregation Control Protocol (LACP)

“Configuring Port Channels”

Security

Ethernet OAM Unidirectional (EOU)

Cisco Nexus 9000 Series NX-OS Security Configuration Guide

Ethernet Interfaces

  • Ethernet interfaces include routed ports.

Cisco Nexus N9K-C9364C-GX and N9K-C93600CD-GX Guidelines and Limitations

  • Beginning with Cisco Nexus NX-OS Release 10.1(2) Auto negotiation is supported for Speed 40G and 100G on NX-OS N9K-C93600CD-GX, N9K-C9316D-GX and N9K-C9364C-GX .

Cisco Nexus N9K-X9400-16W Guidelines and Limitations

Beginning with Cisco Nexus NX-OS Release 10.5(1), the following guidelines and limitations are applicable:

Access ports

An access port is a Layer 2 switchport that carries traffic for only a single VLAN. This type of port is a Layer 2 interface only.

For more information on access ports, see the “Information About Access and Trunk Interfaces” section.

Routed Ports

A routed port is a physical port that can route IP traffic to another device. A routed port is a Layer 3 interface only.

For more information on routed ports, see the “Routed Interfaces” section.

Management Interface

You can use the management Ethernet interface to connect the device to a network for remote management using a Telnet client, the Simple Network Management Protocol (SNMP), or other management agents. The management port (mgmt0) is autosensing and operates in full-duplex mode at a speed of 10/100/1000 Mb/s.

For more information on the management interface, see the Cisco Nexus 9000 Series NX-OS Fundamentals Configuration Guide.

Port-Channel Interfaces

A port channel is a logical interface that is an aggregation of multiple physical interfaces. You can bundle up to 32 individual links (physical ports) into a port channel to improve bandwidth and redundancy. For more information about port-channel interfaces, see the “Configuring Port Channels” section.

Subinterfaces

You can create virtual subinterfaces using a parent interface configured as a Layer 3 interface. A parent interface can be either a physical port or a port-channel. A parent interface can be a physical port. Subinterfaces divide the parent interface into two or more virtual interfaces on which you can assign unique Layer 3 parameters such as IP addresses and dynamic routing protocols.

Loopback Interfaces

A loopback interface is a virtual interface with a single endpoint that is always up. Any packet that is transmitted over a virtual loopback interface is immediately received by that interface. Loopback interfaces emulate a physical interface. For more information about subinterfaces, see the “Loopback Interfaces” section.

Breakout interfaces

A breakout interface is a high-speed network port feature that:

  • splits a single high-bandwidth physical port into multiple lower-speed logical interfaces,

  • enables a switch or router to connect to several lower-speed devices simultaneously, and

  • maximizes port utilization by allowing flexibility in network configuration.

Cisco NX-OS supports the breakout of a high-bandwidth interface into one or more low bandwidth interfaces at the module level or at the per-port level.

Module Level Breakout

Module Level Breakout allows certain high-density ports on a switch module to be split into multiple lower-bandwidth ports, providing increased flexibility and customization in network configurations.

You can configure the interface breakout command to split a high bandwidth interface of a module into multiple lower speed ports.

Some modules breakdowns the all the ports to 4x10G. 4x25G, 4x50G, 4x100G, 2x50G, 2x100G.

For example, a module level breakout 4X10G implies that high bandwidth 40G interface is broken down into four 10G interfaces. The module is reloaded and the configuration for the interface is removed when the command is executed.

The following is an example of the command: 

switch# configure terminal
switch(config)# interface breakout module 1
Module will be reloaded. Are you sure you want to continue(yes/no)? yes

The no interface breakout module module_number command undoes the breakout configuration. In the above example of 4x10G interface, all interfaces of the module in 40G mode and deletes the configuration for the previous 10G interfaces.

Lane Selectors (concept)

A lane selector is a control panel feature that

  • consists of a push-button switch and four LEDs,

  • enables users to view the link or activity status of switch ports, and

  • supports switching between 1 x 40G and 4 x 10G configurations on compatible Cisco Nexus 9000 Series switches and the Cisco Nexus 3164 and 3232 switches.

Additional information

Lane selectors are located on the left side of the Cisco Nexus switch front panel and are labeled 'LS'.

When used in a 1 x 40G configuration, LEDs indicate the link/activity status of the main port. When configured for 4 x 10G, pressing the push button cycles the LEDs through the status of each 10G port. On the last press, all LEDs extinguish, and the display resets to the default mode.

By pressing the lane selector push button, the port LED shows the selected lane’s link/activity status.

The first time the push button is pressed, the first LED displays the status of the first port. Pressing the push button a second time displays the status of the second port, and so on. To display the status of each of the four ports, press the push button as described.

When you press the push button after displaying the status of the last port, all four LEDs extinguish, indicating that the lane selector has returned to display the status for the default 1 x 40G configuration.

Examples

If port 60 is configured as 4 x 10G, pressing the lane selector once displays the link status of 60/1/1, twice for 60/1/2, and so on.


Note

The lane selector does not manage ports not configured for link/activity monitoring.
Guidelines

When a port is in 10G breakout mode and no lane is selected, the 40G port's LED lights green, even if only one of the 10G breakout ports is up.

A 10G breakout port's LED blinks when the beacon feature has been configured for it.

Support for Breakout Interfaces

The table provides detailed information of the supported or not supported breakout modes. For more information, see Cisco Nexus Data Sheets.

Table 2. Breakout Modes Support Matrix

Switches

4x10G

4x25G

2x50G

2x100G

2x200G

2x400G

4x50G

4x100G

8x100G

Nexus 9300-FX3 Platform Switches

N9K-C93108TC-FX3P

N9K-C93180YC-FX3

Yes

Yes

Yes

No

No

No

No

No

No

N9K-X9636C-RX

Yes

Yes

Yes

No

No

No

No

No

No

N9K-X9636C-R

Yes

Yes

Yes

No

No

No

No

No

No

N9K-X9636Q-R

Yes

No

No

No

No

No

No

No

No

N9K-X96136YC-R

No

No

No

No

No

No

No

No

No

N3K-C3636C-R

Yes

Yes

Yes

No

No

No

No

No

No

N3K-C36180YC-R

Yes

Yes

Yes

No

No

No

No

No

No

N9K-93108TC-FX3P

Yes

Yes

Yes

No

No

No

No

No

No

N9K-93108TC-EX

Yes

Yes

Yes

No

No

No

No

No

No

N9K-93180YC-EX

Yes

Yes

Yes

No

No

No

No

No

No

N9K-93108TC-FX

Yes

Yes

Yes

No

No

No

No

No

No

N9K-93180YC-FX

Yes

Yes

Yes

No

No

No

No

No

No

N9K-9348GC-FXP

Yes

Yes

Yes

No

No

No

No

No

No

N9K-X9732C-EX

Yes

Yes

Yes

No

No

No

No

No

No

N9K-X9736C-EX

Yes

Yes

Yes

No

No

No

No

No

No

N9K-X9732C-EXM

Yes

Yes

Yes

No

No

No

No

No

No

N9K-X9736C-FX

Yes

Yes

Yes

No

No

No

No

No

No

N9K-X9736Q-FX

Yes

No

No

No

No

No

No

No

No

N9K-X9788TC-FX

Yes

Yes

Yes

No

No

No

No

No

No

N9K-X9732C-FX

Yes

Yes

Yes

No

No

No

No

No

No

N9K-C9348GC-FXP

Yes

Yes

Yes

No

No

No

No

No

No

N9K-C9336C-FX2

Yes

Yes

Yes

No

No

No

No

No

No

N9K-C93216TC-FX2

Yes

Yes

Yes

No

No

No

No

No

No

N9K-C93360YC-FX2

Yes

Yes

Yes

No

No

No

No

No

No

N9K-C9364C-GX

Yes

Yes

Yes

No

No

No

No

No

No

N9K-C9316D-GX

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

No

N9K-C93600CD-GX

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

No

N9K-X9716D-GX

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

No

N9K-C9364D-GX2A

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

No

N9K-C9332D-GX2B

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

No

N9K-C9348D-GX2A

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

No

N9K-X9400-16W

Yes

Yes

Yes

Yes

No

No

Yes

No

No

N9K-X9400-8D

Yes

Yes

Yes

Yes

Yes

No

Yes

Yes

No

N9K-X98900CD-A

Yes

Yes

No

Yes

Yes

No

Yes

Yes

No
Guidelines and Limitations for Breakout

  • Cisco Nexus 9516 switch does not support breakout on Modules 8 to 16.

  • Beginning with Cisco NX-OS Release 7.0(3)F2(1), the 36-port 100-Gigabit Ethernet QSFP28 line cards (N9K-X9636C-R) and 36-port 40-Gigabit Ethernet QSFP+ line cards (N9K-X9636Q-R) support breakout of 4x10-Gigabit.

  • Beginning with Cisco NX-OS Release 9.2(1), N9K-9636C-R, N9K-X9636Q-R and N9K-X9636C-RX line cards support break out of 40G ports into 4x10 Gigabits.

  • Beginning with Cisco NX-OS Release 9.2(2), N9K-X9636C-R and N9K-X9636C-RX line cards support break out of 100G ports into 4x25 Gigabits. The N9K-C9636C-R does not support RS-FEC.

    Beginning with Cisco NX-OS Release 9.3(3), the default FEC mode on N9K-X9636C-R and N9K-X9636C-RX is FC-FEC for 25Gx4 and 50Gx2. When you connect N9K-X9636C-RX to N9K-X9636C-R, you must configure FC-FEC on N9K-X9636C-RX, because RS-FEC is not supported.

    The N9K-X96136YC-R line card does not support breakout.

  • Beginning with Cisco NX-OS Release 9.3(3), these switches support breakout.

    • Cisco Nexus 93600CD-GX switch

    • Cisco Nexus 9500 R-Series switches support break out of 100G ports into 2x50 Gigabits.

      On Nexus 9500 R-Series switches with N9K-X9636C-R and N9K-X9636C-RX line cards, limited optics (QSFP-100G-PSM4-S, QSFP-100G-AOC, QSFP-100G-CU1M -CU3M) support 2x50G and 4x25G breakout. For more information see Cisco Optics-to-Device Compatibility Matrix.

Best practice for manual breakout configuration

You must use the interface breakout module module number port port range map breakout mapping command when performing manual breakout on Cisco Nexus devices.

  • When you upgrade a Cisco Nexus 9000 device to Cisco NX-OS Release 7.0(3)I7(2) or later, interfaces configured with manual breakout using a QSA are no longer supported. You must remove the configuration and manually reconfigure the breakout settings for the affected interface.


    Note

    As of Cisco NX-OS Release 7.0(3)I7(2), manual breakout of QSA ports is not supported.

    Note

    This restriction does not apply to the following platforms, where manual breakout remains fully supported—N9K-C93128TX, N9K-9332, N9K-C9396PX, N9K-C9396TX, N9K-C9372PX, N9K-C9372TX, N9K-C9332PQ, N9K-9432PQ, N9K-9536PQ, N9K-9636PQ, N9K-X9632PC-QSFP100, N9K-X9432C-S, N3K-C3132Q-V, N3K-C3164Q, N3K-C3132C, N3K-C3232C, N3K-C3264Q, N3K-C3264C, N3K-3064Q, N3K-3016, N3K-3172—because manual breakout is supported on these platforms.

  • Manual breakout is supported on the following platforms because auto-breakout does not does not occur successfully on them—N9K-C93128TX, N9K-9332, N9K-C9396PX, N9K-C9396TX, N9K-C9372PX, N9K-C9372TX, N9K-C9332PQ, N9K-C93120TX, N9K-9432PQ, N9K-9536PQ, N9K-9636PQ, N9K-X9632PC-QSFP100, N9K-X9432C-S, N3K-C3132Q-V, N3K-C3164Q, N3K-C3132C, N3K-C3232C, N3K-C3264Q, N3K-C3264C, N3K-3064Q, N3K-3016, N3K-3172.

Forward error correction (FEC) settings for breakout ports

FEC is required on all cable types except for 1-meter and 2-meter passive copper cables. Cisco switches use FC-FEC CL74 by default. You can configure RS-FEC Consortium 1.6, RS-FEC IEEE, and other FEC algorithms.


Note

Auto-FEC is not supported in Cisco NX-OS Release 7.0(3)I7(x)

There are two primary FEC algorithms used in 25G Ethernet.

    • FC-FEC (also known as "FireCode," "BASE-R," or "Clause 74") provides low-latency error protection (under 100 nanoseconds) optimized for bursty error correction. It is used on 3- and 5-meter passive copper cables, as well as on active optical 25G cables up to 10 meters in length. This FEC type is also utilized across all 100G interfaces.

    • RS-FEC (also referred to as "Reed Solomon," "Clause 91," or "Clause 108") offers better error protection. It is required for 25G multimode fiber (MMF) transceivers, such as Cisco SFP-25G-SR-S, supporting distances up to 100 meters. RS-FEC may also be necessary for active optical cables exceeding 10 meters.

    All 25G devices support FC-FEC by default. The Cisco Nexus 9300-FX series supports RS-FEC.

    Beginning with Cisco NX-OS Release 7.0(3)I7(3,) there are two additional options to configure FEC such as rs-cons16 and rs-ieee as per IEEE standards.

    Enable the RS FEC IEEE (25G) using the fec rs-ieee command on Cisco Nexus 9000 switches to implement RS-FEC error correction on high-speed Ethernet interfaces. 

    switch# (config-if)# fec ?
auto FEC auto
fc-fec CL74(25/50G)off Turn FEC off
rs-cons16 RS FEC Consortium 1.6 (25G)
rs-fec CL91(100G) or Consortium 1.5 (25/50G)
rs-ieee RS FEC IEEE (25G)

  • Beginning with Cisco NX-OS Release 7.0(3)I7(7), you can display the admin and operational status of FEC interface information with the show interface fec command.

    Example: 
    
switch# show interface fec
---------------------------------------------------------------------------------------------------
Name		Ifindex	Admin-fec 	Oper-fec    Status 	Speed 	Type
---------------------------------------------------------------------------------------------------
Eth1/1  	0x1a000000	auto		auto	connected     10G	 SFP-H10GB-AOC2M
Eth1/2  	0x1a000200   			Rs-fec    notconneced    auto	QSFP-100G-AOC3M
Eth1/3/1	0x38014000	auto		auto	disabled	auto	QSFP-H40G-AOC3M
Eth1/3/2	0x38015000	auto		auto	disabled	auto	QSFP-H40G-AOC3M
Eth1/3/3	0x38016000	auto		auto	disabled	auto	QSFP-H40G-AOC3M
Eth1/3/4	0x38017000	auto		auto	disabled	auto	QSFP-H40G-AOC3M
Cisco Nexus 9000 C93180LC-EX switch - Operation and breakout modes

Operation and breakout modes are switch configuration profiles. These profiles let you group and set ports, split high-speed physical ports into multiple lower-speed logical ports, and find out which types of equipment and cabling you can use for each mode.

Cisco Nexus 9000 C93180LC-EX modes

Operation modes are switch configuration profiles that

  • determine available bandwidth and port groupings

  • enable different breakout capabilities, and

  • require you to use distinct configuration procedures to switch between modes.

The Cisco Nexus 9000 C93180LC-EX switch supports three operation modes (7.0(3)I7(1) and later):

  • Mode 1: 28 x 40G + 4 x 40G/100G (Default configuration)

    This is a hardware profile port mode 4x100G + 28x40G ports. It supports:

    • Breakout support of 10 x 4 on top ports from 1 to 27 (ports 1,3,5, 7...27).

      If you break out any of the top ports, the corresponding bottom port becomes non-operational.

      For example, if port 1 is broken out, port 2 becomes non-operational.

    • 1 Gigabit and 10 Gigabit QSA support on ports 29, 30, 31, and 32. However, QSAs on the top and bottom front panel ports must be of same speed.

    • Breakout support of 10 x 4, 25 x 4, and 50 x 2 on ports 29, 30, 31, and 32.

  • Mode 2: 24 x 40G + 6 x 40G/100G

    This hardware profile port mode 6 x 100G + 24 x 40G ports. It supports:

    • Breakout support of 10 x 4 on top ports from 1 to 23 (ports 1,3,5, 7...23). If any of the top port is broken out the corresponding bottom port becomes non-operational.

    • Breakout support of 10 x 4, 25 x 4, and 50 x 2 on ports 25, 27, 29, 30, 31, and 32.

    • 1 Gigabit and 10 Gigabit QSA support on ports 29, 30, 31, and 32. However, QSAs on the top and bottom front panel ports must be of same speed.

  • Mode 3: 18 x 40G/100G

    This hardware profile port mode 18 x 100G that ports. It supports:

    • Breakout support of 10 x 4, 25 x 4, and 50 x 2 on top ports from 1 to 27 (ports 1,3,5, 7...27) and on ports 29,30,31,32.

    • 1 Gigabit and 10 Gigabit QSA on all the 18 ports.

To change from Mode 3 to another mode, enter the copy running-config startup-config command followed by reload command to take effect. However, to move between Modes 1 and 2, you only need to enter the copy running-config startup-config command.

Use the show running-config | grep portmode command to display the current operation mode. 


            switch(config-if-range)# show running-config | grep portmode
            
            hardware profile portmode 4x100G+28x40G
Breakout modes

The Cisco Nexus C93180LC-EX switch has three breakout modes.

  • Support for 40G to 4 x 10G breakout ports

    • This mode enables the breakout of 40G ports into 4 x 10G ports.

    • To configure this mode, use the interface breakout module 1 port x map 10g-4x command.

  • Support for 100G to 4 x 25G breakout ports

    • This mode enables the breakout of 100G ports into 4 x 25G ports.

    • To configure this mode, use the interface breakout module 1 port x map 25g-4x command.

  • Support for 100G to 2 x 50G breakout ports

    • This mode enables the breakout of 100G ports into 2 x 50G ports.

    • To configure this mode, use the interface breakout module 1 port x map 50g-2x command.

Breakout considerations for Cisco Nexus 9000 C9364C-GX switch

hese are breakout considerations for Cisco Nexus N9K-C9364C-GX switches.

  • Configure breakout modes—1-64, 2 x 50G, 4 x 25G, and 4 x 10G —only on odd-numbered ports.


    Note

    Do not attempt break out on even-numbered ports.

  • When you break out an odd-numbered port, even-numbered ports in that quad are automatically removed, and the other odd port is configured to the same breakout speed.

    For example, if port 1 or port 3 is broken out into 2 x 50, 4 x 25G or 4 x 10G, then the other odd port in that quad is automatically set to the same speed and ports 2 and 4 in that quad are removed. All ports in that quad revert to default when this breakout configuration is removed.

  • To revert a quad to default port status, remove the breakout configuration from both odd ports in the quad.

  • QSFP28 (100G) transceivers support the 4 x 25G breakout feature. Beginning Cisco NX-OS Release 9.3(5), the 2 x 50G breakout feature is supported.

  • QSFP+ (40G) transceivers support the 4 x 10G breakout feature.

  • Use the interface breakout module 1 port x map 50g-2x command to enable the breakout of 100G ports into 2 x 50G ports on all odd ports.

  • Use the interface breakout module 1 port x map 10g-4x command to enable the breakout the breakout of 40G ports into 4 x 10G ports.

Breakout features on Cisco Nexus 9000 C93600CD-GX switches

Use the breakout considerations on the Cisco Nexus N9K-C93600CD-GX.

  • In Cisco Nexus N9K-C93600CD-GX, every four ports from 1 through 24 are referred to as a quad.


    Note

    The breakout configuration and the speed must be the same within a quad.

    The breakout feature may not function as expected if there is a mismatch of speed or breakout configuration within a quad.

    The six quads consist of ports 1–4, 5–8, 9–12, 13–16, 17–20, and 21–24.

  • Beginning Cisco NX-OS Release 9.3(5), 2 x 50G breakout feature is supported on ports 1-36.

  • 4 x 25G and 4 x 10G breakout features are supported only on odd ports, between ports 1 through 24. The even ports within a quad are removed (four ports).

  • When an odd-numbered port in a quad is broken out, the even ports in that quad are removed and the other odd ports within the quad is broken out automatically broken out to the same speed.

    For example, if port 1 is broken out into 4 x 25G or 4 x 10G, the other odd ports within the quad are automatically broken out to the same speed, and ports 2 and 4 in that quad are removed. When this breakout configuration is removed, all ports in that quad revert to the default configuration.

  • 2 x 50G breakout is supported on all ports from 1 through 24. All ports in a quad are broken out automatically to the same speed when one port in the quad is broken out to 2 x 50G.

    For example, when Port 2 is broken out into 2 x 50G, ports 1, 3, and 4 are automatically broken out into 2 x 50G.


    Note

    Only RS-FEC is supported on both lanes for 50G speed on ports 1 through 24.

  • Beginning with Cisco NX-OS Release 9.3(3), ports 25-28 support 4 x 10G, 4 x 25G, and 2 x 50G breakout features. These breakout features are supported in port pairs, for example 25-26 and 27-28.


    Note

    Lane 2 of 2 x 50G should be configured with RS-FEC for the link to be up.

  • Beginning with Cisco NX-OS Release 9.3(3), ports 29-36 support these breakout configurations.

    • QSFP-DD-400G-DR4 transceivers support only the 4 x 100G breakout feature.

    • QSFP-DD-400G-FR4 and QSFP-DD-400G-LR8 transceivers do not support the breakout features.

    • QSFP28 (100G) transceivers support 2 x 50G and 4 x 25G breakout features.

    • QSFP+ (40G) transceivers support 4 x 10G breakout features.

Breakout considerations on Cisco Nexus C9316D-GX switches

Use these breakout considerations for ports 1 through 16 on the Cisco Nexus N9K-C9316D-GX switch.

  • QSFP-DD-400G-DR4 transceivers support only the 4 x 100G and 4 x 10G breakout features.


    Note

    QSFP-DD-400G-FR4 and QSFP-DD-400G-LR8 transceivers do not support the breakout features.

  • QSFP28 (100G) transceivers support the 2 x 50G, 4 x 25G, and 4 x 10G breakout feature.

USB ports on Cisco NX-OS switches (concept)

USB ports on Cisco NX-OS switches are configurable hardware interfaces that

  • support connecting external storage or devices,

  • can be administratively enabled or disabled to increase security, and

  • require switch reloads to apply enable/disable changes.

The USB ports on the Cisco NX-OS switches are enabled by default. You can disable or enable all the USB ports.

Disable USB ports

To disable USB ports, use the port usb disable command. 

switch(config)# port usb disable
switch(config)# copy running-config startup-config
switch(config)# reload

Note

This command requires a reload.

Enable USB ports

To enable USB ports if previously disabled, use no port usb disable command 

switch(config)# no port usb disable
switch(config)# copy running-config startup-config
switch(config)# reload

This command requires a reload.


Note

For changes to take effect on already inserted USB, we recommend you to use the copy running-config startup-config command and reload the switch.

Virtual Device Contexts

Cisco NX-OS can segment operating system and hardware resources into virtual device contexts (VDCs) that emulate virtual devices. The Cisco Nexus 9000 Series switch does not support multiple VDCs. All switch resources are managed in the default VDC.

High Availability for Interfaces

Interfaces support stateful and stateless restarts. A stateful restart occurs on a supervisor switchover. After the switchover, Cisco NX-OS applies the runtime configuration.